Thermoresponsive switch means



June 19, 1956 R. J. CASSIDY 2,751,465

THERMORESPONSIVE SWITCH MEANS Filed Sept. 10, 1954 INVENTOR.

FLZBZJZTJ 51551272".

THERMGRESPONSIVE SWITCH MEANS Robert J..Cassidy, Mansfield, Ohio,assignor to Pace, ind,

Mansfield, ()hio, a corporation or" @hio Application September lil,1954, Seriai No. 455,174

11 Claims. (Cl. 200139) his invention relates to switch mechanisms andmore especially "to adjustable switch mechanisms embodying.thermo-responsive .means for maintaining automatic control-of a circuitof a heating means or heating unit.

Switch mechanisms embodying thermoresponsive means for controlling thetemperature of heating elements have heretofore incorporated aninsulating means associated with the thermoresponsive means engageablewith a switch armor contact-carrying strip, such arrangement controllingan electrical circuit through the flexure or relative movement of athermoresponsive element caused 'by variations in temperature. It hasbeen conventional practice to utl-ize a pin or member formed of ceramic,lava'or-other-suitable high temperature resistant material permanentlysecured to the thermoresponsive means and adapted for engagement with acontact-carrying strip. The insulating member has heretofore been formedwith an annular lterf or groove, and the thermoresponsive means in theform of a bimetallic strip or element has been provided with a recessfor receiving the button and wherein adjacent portions of the bimetalelement are distorted or bent -into the kerf or groove to hold theelement and member in assembled relation. The prior methods of securingthe member formed of ceramic or lava to abimetal element involve swagingor distorting the metal of the elementinto the kerf in the element, andthis operation affects the thermoresponsive characteristics of the,bimetal element, impairing the accuracy of its functioning.Furthermore, as temperature variations adjacent the .bimetal elementcause expansion and contraction of the element, the member of insulatingmaterial becomes loosened after a comparatively short period ofoperation.

Such lost'motion or looseness causes the operation of the bimetalelement to become unstable and unreliable for controlling the operationof the switch mechanism at a r 3 selected temperature.

The present invention has for an object the provision of a novel methodand means of connecting a member of insulating material with athermoresponsive means so as to secure eificient and reliablefunctioning of the thermoresponsive means.

An object of the invention is the provision of a means for connecting amember of high temperature resistant insulating material withabimetallic element through the medium of a securing means engageablewith the insulating member and the bimetallic element in a manner toreliably hold the parts in assembled relation without any looseness orlost motion and providing a means which will hold the parts togetherwhen subjected to variations in temperature without impairing therigidity of the connection.

Another object of the invention resides in a method of securing aninsulating member of high temperature resistant material to a bimetallicunit wherein the insulating member extends through an opening in thebimetallic unit and a retaining member engaged with the insulatingmember and the bimetallic element, this arrangement providing a rigidconnection between the bimetallic element and insulating member whichwill not become dislodged or impaired over long periods of use.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of construction and tocombinations of parts, elements per se, and to economies of manufactureand numerous other features as will be apparent from. a consideration ofthe specification and drawing of :aform of the invention, which may bepreferred, in which:

Figure l is an enlarged side elevational view of a thermostat switchconstruction embodying a form of the invention;

Figure 2 is an enlarged end view of a portion of the construction shownin Figure 1;

Figure 3 is a view taken substantially on the line '33 of Figure 2;

Figure 4 is a bottom plan View of the construction shown in Figure 3;

Figure 5 is a greatly enlarged view of securing means forming part ofthe invention;

Figure 6 is an enlarged detail sectional view taken substantiaiiy on theline 6-6 of Figure 2, and

Figure 7 is a view similar to Figure 6 illustrating a step in the methodof applying an insulating member securing means to the bimetal-element.

While the arrangement of the invention is illustrated as utilized in athermostat switch construction for use with electrical appliances, it isto be understood that the arrangement of the invention may be used withany mechanism wherein the same may be found to be applicable.

Referring to the drawings in detail, there is illustrated in Figure l aportion E0 of an electrical appliance such, for example, as an electriciron provided with a heating element 12 to which electrical energy issupplied through supply conductors or lines L1 and L2. The portion '10of the appliance provides a support for a switch mechanism which is bothmanually and thermostatically controlled. The switch construction isshown enlarged to about twice actual size and is inclusive of a plate ormember 1.6 upon which is mounted a member or sleeve it? provided with atenon 29 which fits into an opening formed in the plate in and is swagcdor staked as at 22 to fixedly secure the sleeve 13 to the platelo.

The interior of the sleeve 1.8 is threaded to receive a threaded portion24 of a member 25 forming an element of the manual control means for theswitch mechanism. Secured to member 25 is an arm 27 provided with afinger piece 23 for manipulating or rotating the arm 27 and member 25relative to the sleeve 18 for adjusting the position of acontact-carrying switch member or flexible strip 30. The member 25 isinteriorly bored and threaded to receive a member 32, provided with akerf 33 to facilitate rotation of member 32 with respect to member 25 tosecure initial adjustment of member 32 for a purpose hereinafterdescribed. The lower end of member 32 is formed with a socket 34 toreceive the upper end of a pin 36 formed of ceramic, lava or other hightemperature resistant insulating material. The lower end of the pin 36is fashioned to a generally Wedge-like shape 37 which is received in agenerally rectangularly shaped opening or depression formed in theswitch member 30. The switch member 3!) is provided with a contact 39which is arranged for cooperation with a contact 41 carried by a secondswitch member or flexible strip 42. The pin .36 extends through aclearance opening 43 in the uppermost switch member 42.

A thermoresponsive means in the form of a bimetallic element 45,comprising two dissimilar metals having different coefficients ofexpansion, is disposed coincident with a portion of the appliance 10 soas to be directly subjected to and influenced by heat generated byresistance to the passage of an electric current through the heatingelement 12. An extremity of the bimetallic element 45 is provided withan insulating member 43 which is secured to the bimetallic element in amanner hereinafter described. The insulating element 48 is adapted forengagement with the flexible switch member 42 for a purpose hereinafterexplained.

Means is provided for securing the switch arms or flexible strips 30 and42 and the bimetallic element 45 in predetermined relation as a unit asillustrated in Figure 1. A metal member 54 of disk-like configuration isformed with an upwardly extending, thin-walled sleeve portion 52 whichextends through an opening in the plate 16, and after assembly of thebimetallic element 45, switch members 30 and 42 and insulating washers,the upper end of the sleeve is swaged or spun to a configuration shownat 54. The bimetallic element 45 has an opening to receive the sleeve 52and is insulatingly supported from the sleeve by means of an insulatingwasher 55.

The flexible switch member 30 and an adjacent connector or terminalmember 57 are provided with openings which receive tenons formed on awasher 58 of insulating material, whereby the member 30 and terminal 57are insulatingly supported upon the sleeve 52. The switch member 42 anda second terminal 6% in contact therewith are formed with registeringopenings to receive a tenon formed on a washer 62 of insulating materialwhereby the switch member 42 and connector 64 are also carried by andinsulated from the sleeve 52. Through the provision of members 55, 58and 62 the current-conducting terminals 57 and 60 and the flexiblestrips forming switch members 39 and 42 are insulated from the othercomponents of the switch construction.

The terminals 57 and 60 are adapted to be connected respectively withthe current supply conductor L1 and a conductor L3. The supply conductorL2 and conductor L3 are connected with the heating element 12 of theappliance. The switch assembly may be mounted upon the appliance throughthe use of a bolt 64 extending through the sleeve 52 of the disk-likemember 50 and into a threaded opening 66 formed in the appliance 10.

The arrangement of the present invention includes a novel means forsecuring the insulating member or button 48 to the end zone of thebimetallic member 45. The button or pin 48 formed of ceramic or lava isprovided with a head 70. The end zone of the bimetallic element 45 isprovided with a circular opening 72 which is of slightly larger diameterthan that of the body portion 49 of pin 48 and is adapted to receive thebody of the pin as particularly shown in Figures 2, 3, 6 and 7, the head70 engaging the lower surface of the bimetallic element 45.

Means is provided for fixedly securing the pin or button 48 to thebimetallic member 45. The form of means illustrated is a retainer, clipor locking member which is illustrated in the enlarged view of Figure 5.The clip or locking member 75 is formed of sheet metal such as stainlesssteel or the like tempered to provide a degree of resiliency orflexibility so that the inherent resiliency in the clip functions tohold the button 48 in position. The clip 75 is formed with a bodyportion 77 having transversely extending ear portions 79 which arefashioned to U-shaped configuration as shown in Figure 5. One edge zoneof the body portion 77 is formed with a struck-up or bent-up lug orabutment portion 80. The body portion 77 is also fashioned with a raisedportion 82, preferably of spherical shape, which is adapted to engagethe button substantially at the central zone thereof. As shown in Figure3, the edges or edge zones of the bimetal element 45 are taperedslightly in the direction toward the end thereof equipped with thebutton 48. The bight portions 84 of U-shaped projections 79 are providedwith a similar taper as shown in Figure 3-so that in the assembly of theclip 75 with the bimetallic element 45, the edge zones of the latterwill be engaged by the tapered surfaces of the bight portions 84.

"Figure 6 illustrates the clip 75 in final assembled relaiton with thebimetal element 45 and the lava pin or button 48. Figure 7 illustrates astep in the method of assembling the clip 75 with the bimetal elementand the button. In assembling the button and clip to the bimetallicelement, the body or shank 49 of the button or pin 43 is inserted in theopening '72 in the bimetal element 45 with the head portion incontiguous or engaging relation with the lower surface of the bimetallicelement as shown in Figure 7. The clip is slipped over the end zone ofthe bimetal element 45 with the body portion 77 adjacent the headportion 70 of the button and the U-shaped projections 79 overtaking oroverlying the edge zones of the bimetallic element 45 as in the mannerparticularly shown in Figures 2, 3 and 4.

The clip 77 is advanced to the position shown in Figure 7 until thestruck-up or raised portion 80 extends beyond the peripheral edge of thehead portion 70 of button 48. The metal of the struck-up portion orabutment 80 is sufiiciently resilient so that the abutment 80 is flexedas it is slidably moved across the head 70. In this position the raisedportion 82 is in snug engagement with the central zone of the lowersurface of the head 70. After the parts are in the position shown inFigure 7, the assembler then slides the retaining clip 75 in a righthand direction as viewed in Figure 7 to the position shown in Figure 6.In this position, the body portion 49 of the button 43 engages an outeredge wall of the opening 72 in the bimetallic element 45 defining theopening 72, the said portion of the edge wall serving as a positioningor abutment means for properly locating the button 48 with respect tothe bimetal element shown in Figure 6. The clip 75 in its assembledposition is disposed as shown in Figure 6 with the raised or struck-upportion 80 engaging a peripheral edge zone of the head 70, thearrangement serving to prevent dislodgement of the clip 75.

The inherent fiexure in the clip 75 securely retains the button 48 inits proper position. Expansion or contraction of the elements iscompensated by the resilient or flexible characteristics of the clipconstruction 75, and the clip is maintained in snug engagement with thebimetallic element 45.

In the event the button 48 becomes broken, necessitating repair orreplacement, the clip 75 may be readily removed by bending or distortingthe raised portion 80 downwardly out of contact with the head 70 of thebutton after which the clip may be slidably removed from the end zone ofthe bimetallic element 45.

The switch mechanism embodying the invention is especially usable forregulating the temperature of electrical appliances. In operation of thedevice, the terminals 57 and 60 are connected in series with the heatingelements 12 which receive electrical energy from electrical energysupply lines L1 and L2. The bimetallic element or thermostat 45 isresponsive to the heat generated by the passage of electrical energythrough the resistance or heating units 12. The manual means 27 may beadjusted to a position predetermining the location of the contact 39 sothat, upon flexure of the bimetallic element 45 set up by heat energyfrom the heater 12, the button or member 48 carried by the element 45engages the flexible strip or switch arm 42 to elevate contact 41 andinterrupt the circuit through the heating elements 12. By modifying therelative position of the contact 39 through the manually adjustablemeans 27, the temperature of the appliance and the temperature ambientthe switch mechanism may be controlled. Through the present arrangementof means for securing the insulating member 48 to the bimetallic memberor thermostat 45, the thermostat is free to respond to variations intemperature without affecting the securing means holding the member 48to the thermostat. Furthermore, in event of damage to or breakage of theinsulating member 48, the same may be removed and replaced by removingthe clip 75.

The manually controlled means 27 is rotatable through predeterminedlimits to adjust the position of the thermoresponsive element 45 foroperation in a desired temperature range and cooperates with a scale ormember (not shown) bearing calibrations indicating temperature settingsfor the appliance. The member 32 is threadedly connected with the sleeveand is adapted to be rotated or adjusted to determine the temperaturerange of the manually operable means 27. The member 32 may be adjustedby means of a suitable tool inserted in the kerf 33 to move the switchmember within a desired working range of the thermoresponsive means 45.After the initial adjustment of member 32 has been completed, acementitious or bonding material may be applied as shown in the drawingsat 85 to prevent further rotation of member 32 relative to the sleeve25. A resinous bonding material or solder may be utilized for thepurpose. It is preferred to use a bonding material of a characterpermitting the bond to be readily broken or disrupted in the event itbecomes necessary to readjust the relative position of the switch member30.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than is herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

I claim:

1. Apparatus of the character disclosed, in combination, switch meanshaving flexible current-conducting members, a thermoresponsive means, aninsulating member carried by said thermoresponsive means and arrangedfor engagement with one of said flexible current-conducting means formoving the latter upon variations in temperature, and a retaining memberhaving portions engaging the thermoresponsive means and a centrallydisposed raised portion engaging said insulating member for securing theinsulating member to the thermoresponsive means.

2. Apparatus of the character disclosed, in combination, switch meanshaving flexible current-conducting members, manually operable means foradjusting the relative position of one of said flexiblecurrent-conducting means, a thermoresponsive element, an insulatingmember carried by said thermoresponsive means and engageable with theother of said flexible current-conducting means for controlling theposition of the latter upon ambient temperature changes, said insulatingmember having a portion extending through an opening in thethermoresponsive means and a head portion engaging a surface ofthermoresponsive means, and a retaining member having means engaging thethermoresponsive means and the head portion of the insulating member forsecuring the insulating member to the thermoresponsive means.

3. Apparatus of the character disclosed, in combination, switch meanshaving flexible current-conducting members, manually operable means foradjusting the relative position of one of said flexiblecurrent-conducting means, a thermoresponsive means having an openingtherein, an insulating member carried by said thermoresponsive means andarranged for engagement with the other of said flexiblecurrent-conducting means for moving the latter under the influence ofchanges in temperature, said insulating member having a portionextending through the opening in the thermoresponsive means, saidinsulating member having a head portion, and a retaining member havingportions engaging the thermoresponsive means and a raised projectionengaging the head portion of said insulating member for securing theinsulating member to the thermoresponsive means.

4. In combination, a support, a pair of switch members anchored to thesupport, said switch members having cooperating contacts, a bimetallicelement anchored to the support, said bimetallic element having acircular opening formed therein, an insulating member formed with a bodyportion extending through the opening and a head portion engaging amajor surface of the element, said insulating member arranged to engageone of said switch members, and a retainer ,formed of sheet metal forholding said member to said element.

5. in combination, a support, a pair of switch'members anchored to thesupport, said switch members having cooperating contacts, a bimetallicelement anchored to the support, said bimetallicelement having anopening formed therein, an insulating member formed with a portionextending through the opening and arranged'to control the position ofone of said switch members, said insulating member having an abutmentengageable with the bimetallic element for positioning said memberrelative to said element, a retainer formed .of sheet metal for holdingsaid member to said-element, said retainer having a struck up portionengageable with the abutment of the insulating member and projectingportions engaging and embracing edge zones of said bimetallic elementfor securing the insulating member against movement relative to saidelement.

6. In combination, a support, a pair of switch members anchored to thesupport, said switch members having cooperating contacts, a bimetallicelement anchored to the support, said bimetallic element having anopening formed therein at a zone spaced from the support, an insulatingmember arranged to control the position of one of said switch members,said insulating member being formed with a shank portion extendingthrough the opening, said insulating member having a head portionengageable with the bimetallic element for positioning said memberrelative to said element, a retainer formed of sheet metal for holdingsaid member to said element, said retainer having a centrally disposedraised portion engageable with the head portion of the insulating memberand U-shaped ear portions engaging the edge zones of said bimetallicelement for securing the insulating member against movement relative tosaid element.

7. In combination, a support, a thermoresponsive means comprising a unitformed of dissimilar metals, said unit having an opening formed therein,a member formed of insulating material having a shank portion and anenlarged head portion, the shank portion adapted to extend through theopening in the unit and the head portion engaging the unit, and a clipformed of sheet metal having laterally opposed portions engaging theedge zones of the thermoresponsive means and a centrally disposed raisedportion engaging the head portion of the insulating member for retainingthe insulating member in the opening in said thermoresponsive unit.

8. In combination, a support, a thermoresponsive means formed ofdissimilar metals, said thermoresponsive means having an opening formedtherein, an insulating member having a shank portion and a head portion,the shank portion adapted to extend through the opening in thethermoresponsive means and the head portion to engage said means, aretainer securing the insulating member in the opening in saidthermoresponsive means, said retainer having a portion engageable withthe head portion of the insulating member and laterally opposed portionsengaging the edge zones of the thermoresponsive means, said retainerhaving a raised tongue adapted to contact the peripheral zone of thehead portion to resist displacement of the retainer.

9. In combination, a support, a thermoresponsive means formed ofdissimilar metals, one end zone of the thermoresponsive means beinganchored to the support, the opposite end zone of the thermoresponsivemeans having an opening formed therein, an insulating member having ashank portion and abutment formed thereon, the shank portion adapted toextend through the opening in the thermoresponsive means and theabutment to engage a surface of said means, a retainer securing theinsulating member in the opening in said thermoresponsive means, saidretainer being formed of sheet metal having a portion engageable withthe abutment of the insulating member and laterally opposed portionsengaging the edges of the thermoresponsive means, said retainer having astruck-up portion adapted to contact the peripheral zone of the headportion to resist displacement of the retainer.

10. A method of assembling a member of insulating material to anelongated bimetallic element having an opening formed therein includingthe steps of inserting the member in the opening in the element,slidably moving a retainer along the element in one direction until aprojection on the retainer is forced beyond the member, and sliding theretainer in the opposite direction whereby the projection carries themember into engaging relation with a wall of the opening of the element.

11. A method of assembling a headed insulating memher to an elongatedbimetallic element having an opening formed therein including the stepsof inserting the insulating member in the opening with the head engagingthe element, slidably moving a retainer over an end zone of the elementuntil flexible projection on the retainer is moved beyond the head ofthe member, and retracting the retainer in the opposite directionwhereby the projection moves the member into engaging relation with awall of the opening in the element.

References Cited in the file of this patent UNITED STATES PATENTS

